Process for wet-refining non-ferrous metals and metal alloys



States PROCESS F011 WET-REFINING NQN-FERROUS idETALS AND METAL ALLOYS Tenn Raymond Vaiere Martiny, Rouen, France No Drawing. Application December 15, 1952, Serial No. 326,143

Claims priority, application France February 19, 1952 5 Claims. (Cl. 75-101) It is known that lead, as an impurity, plays a disastrous part in non-ferrous metals or non-ferrous metal alloys. When its percentage is above 0.5%, its presence namely brings about a decrease in the mechanical features of the subject metals and metal alloys.

It is also known that lead is unaffected by the dryrefining processes and that this operation has to be effected through the wet process, for instance, by subjecting the non-ferrous metal or alloy to be refined to the action of nitric acid in the presence of tartrates, this operation being efiected through the hot process.

The object of my invention is a simplified wet-refining process making it possible to eliminate the lead impurity. My invention mainly consists in subjecting the nonerrous metal or alloy, previously changed into a divided product, to the action of a bath, at ambient temperature, made up of water and nitric acid, to which a surface active agent has been added.

The object of my invention also relates to certain other arrangements as mentioned hereafter and preferably used jointly with the main process as indicated here above.

My invention particularly covers certain methods for applying and carrying out the said arrangements, as also non-ferrous metals and non-ferrous metal alloys prepared through those processes which apply the said arrangements, the apparatuses and installations using the said arrangements and products, as well as articles and objects manufactured with the said metals or alloys.

As an instance, I shall now disclose how my invention is to be carried out.

The non-ferrous metal or metal alloy is turned into a divided products. It is advantageous to start from lathe chips, grinding-machine chips or any other sorts of chips from machine-tools. Preferably, the smallest size of the product used should be of the order of 0.04 millimeter.

The metal or metal alloy divided in this manner is dipped in a bath whose composition is as follows:

100 litres water litres nitric acid, density 1.33 (36 Baum) 0.5 litre sodium alkyl sulphate.

The bath is maintained at ambient temperature.

The amount of non-ferrous metal or metal alloy which can be treated in the above mentioned bath is 50 to 100 kilograms, for instance, in the case of bronze, brass or aluminum scraps.

It will be an advantage if the tank containing the bath is made of cement or ceramic material, or lined inside with the latter materials.

In order to accelerate the refining process, one or more of the means given hereafter may be used.

The bath is stirred through a mechanical stirring rod, or stirred by air, or other gas, in this instance, a neutral gas, forced into the bath liquid.

The tank containing the bath is completely closed, and the bath liquid is poured into it or circulated in it, for instance, through a pump, the said liquid being maintained under pressure.

The process as described permits to bring down the lead percentages in non-ferrous metals or metal alloys, from 25% to 0.50% and less.

It results from the foregoing that by applying the processes as described, it is possible to obtain a particularly economical refining operation, namely to get topgrade metals or alloys from major amounts of metal which could be used only in very inferior manufactures, as also to immediately use scraps from the mechanical machining industry, in order to obtain the metals as described above.

It is obvious that my invention is not limited to the methods of application and utilization as stated; it also embodies all the variants thereof.

What I claim is:

1. A process for eliminating lead impurities from nonferrous metallic materials selected from the group which consists of copper, aluminum and their alloys, comprising the steps of comminuting the material to be purified and immersing the resulting metallic fragments, at ambient temperature, in a diluted aqueous solution of nitric acid having a liquid surfactant admixed with it, the amount of said surfactant being a small proportion of the amount of nitric acid in said solution.

2. A process according to claim 1, wherein said bath is agitated during immersion of said fragments therein.

3. A process according to claim 2, wherein agitation of said bath is carried out by forcing through said bath a fluid selected from the group which consists of air and inert gases.

4. A process according to claim 1, wherein said bath is maintained under pressure during immersion of said fragments therein.

5. A process for eliminating lead impurities from nonferrous metallic materials selected from the group which consists of copper, aluminum and their alloys, comprising the steps of comminuting the material to be purified and immersing the resulting metallic fragments, at ambient temperature, in a diluted aqueous solution of nitric acid having a surface-active agent admixed with it, said agent being a liquid sodium alkyl sulphate present in an amount of the order of 5% of the amount of nitric acid in said solution.

References Cited in the file of this patent UNITED STATES PATENTS 571,369 Hunt Nov. 17, 1896 1,785,245 Bowman Dec. 16, 1930 1,886,411 Mantell Nov. 8, 1932 1,918,817 Mantell July 18, 1933 1,954,743 Peterson Apr. 10, 1934 2,200,139 White May 7, 1940 2,465,750 Reid Mar. 29, 1949 2,509,003 Lathrop et a1 May 23, 1950 2,564,749 Bried Aug. 21, 1951 2,697,660 Sibert Dec. 21, 1954 FOREIGN PATENTS 458,163 Great Britain Dec. 14, 1936 OTHER REFERENCES Holmes, H. N.: General Chemistry, The Macmillan Co., New York, N. Y. (1949), 5th ed., page 545. 

1. A PROCESS FOR ELIMINATING LEAD IMPURITIES FROM NONFERROUS METALLIC MATERIALS SELECTED FROM THE GROUP WHICH CONSISTS OF COPPER, ALUMINUM AND THEIR ALLOYS, COMPRISING THE STEPS OF COMMINUTING THE MATERIAL TO BE PURIFIED AND IMMERSING THE RESULTING METALLIC FRAGMENTS, AT AMBIENT TEMPERATURE, IN A DILUTED AQUEOUS SOLUTION OF NITRIC ACID HAVING A LIQUID SURFACTANT ADMIXED WITH IT, THE AMOUNT OF SAID SURFACTANT BEING A SMALL PROPORTION OF THE AMOUNT OF NITRIC ACID IN SAID SOLUTION. 